There are so many shipwrecks, in fact, that a search operation for the missing Malaysia Airlines Flight 370 has discovered two by accident.

The Battle of the Atlantic
alone, which spanned nearly six years during World War II, claimed over
3,500 merchant vessels, 175 warships, and 783 submarines.

Particularly
interesting are the cargo ships that literally contain treasure, such
as Spanish galleons that transported gold and jewels across the
Atlantic.

The Uluburun shipwreck
off the coast of southwestern Turkey is roughly 3,300 years old, and
that Late Bronze Age vessel contained gold, silver, jewels, copper and
tin ingots, tools, swords and other weapons, and much more trade
cargo—all of it hauled up over the course of 10 years and 22,413 dives.

But
most wrecks don't receive that kind of attention.

In fact, less than 10
percent of the shipwrecks that we we've located—which account for just
10 percent of all shipwrecks in the world—have been surveyed or visited
by divers.

Fishing trawlers snag on sunken ships, sonar readings pick
them up, historical records tell us where they should be, harbor
dredging operations uncover wrecks that have long been lost below the
seafloor—but there simply isn't enough time and money to explore the
vast majority of them.

The Sweepstakes was built in 1867 as a two-masted schooner in Burlington, Ontario by John Simpson.The ship's length is 36.3m (119ft) and lays just below the surface in Big Tub harbor with a maximum depth of 7m (20ft).The Sweepstakes was damaged off Cove Island, then towed to Big Tub harbor where she sank in 1885.At times, the shipwreck will sit well below the surface of Lake Huron and then when the lake becomes shallower, sections of the Sweepstakes rise up out of the water making parts clearly visible.Throughout Fathom Five National Marine Park, there are 22 shipwrecks and many people come here to snorkel and scuba dive in these pristine waters.

Daunting Task

James
Delgado, the Director of Maritime Heritage at the National Oceanic and
Atmospheric Administration (NOAA), says that there are an estimated
4,300 shipwrecks within NOAA's 14 National Marine Sanctuaries.

Of these,
432 have been dived on and surveyed.

And these are shipwrecks within a mapped area set aside for preservation.

"There
are laws and regulations directing NOAA to find what lies in those
waters and assess it," Delgado said in an email.

Similar to other marine
preservation organizations around the world, NOAA is not only devoted
to discovering what the ships are, but also how their presence
might affect the ecology of the marine environments they lie within.

Outside of marine sanctuaries, there isn't as much of an incentive.

Most
shipwrecks are documented for a much simpler reason: to avoid
collisions or other incidents. NOAA's Office of Coast Survey maintains a
database
of about 20,000 ships that is available to the public, primarily for
the benefit of navigators and researchers.

The information for that
database comes from two organizations within NOAA, the Electronic
Navigational Charts (ENC) and the Automated Wrecks and Obstructions
Information System (AWOIS).

Still,
it's difficult to pinpoint exactly where a shipwreck is on the ocean
floor.

The database lists some limitations, including that it "contains
wreck features from two different sources that were created for
different purposes, and there is not a perfect match of features from
either source. The same wreck may be found in both the ENC wrecks and
AWOIS wrecks layers, although the positions may not necessarily agree."

And that
doesn't include the historical and cultural value of excavating
shipwreck sites.

So why don't we explore more of them?

For
one thing, it's hard to know what's worth the time.

Diving operations
can cost millions of dollars, and before we go down there, we have no
idea what the ship is, what it was carrying, and what condition the
cargo is in. In some cases, we are not even 100 percent sure that the
identified object is a ship at all.

"Not many people follow up on a
target to determine if it is a wreck, and if so what type it is, and
then if possible, which ship it is," says Delgado.

There are a number of efforts to change that, such as the Ocean Discovery XPrize
that is offering $7 million in prize money for private teams that build
an autonomous underwater vehicle (AUV) and create a bathymetric map
(like a topographic map, but of the sea floor).

The Schmidt Ocean Institute,
founded by former Google CEO Eric Schmidt, maintains a 272-foot vessel
outfitted with modern oceanographic equipment that scientists can apply
to use for various research expeditions.

The
good news, for shipwrecks explorers at least, is that the majority of
shipwrecks are actually near the coast, with a large percentage of
incidents occurring in and around the entryways to ports and harbors.

"Some harbors are tough to enter, like Oregon's Columbia River Bar, or
leave, like San Francisco's Golden Gate and Bar, due to shifting winds,
shifting sands, fog, storms, or strong tides," says Delgado.

"But also
for the same reason that most auto accidents seem to happen within a
mile of home, and there are many accidents coming in and out of parking
lots, people seem to be less cautious or more aggressive."

But even with advancing AUV technologies and efforts to
map more of the ocean floor, many shipwrecks are likely to remain
unexplored until they are buried below the sands or decay beyond the
point of recognition.